Method of maintaining combustion in furnaces



Dec. 8, 1925. 1,564,542

w. M. DUNCAN METHOD OF MAINTAINING COMBUSTION IN FURNACES Filed Jan. 17.1924 4 Sheets-Sheet 1 HOT WATER #07 AIR AIR com WATER A 7' TOR/YE y:

Dec. 8 1925- 1,564,542

Filed Jan. 17, 1924 4 Sheets-Sheet 2 GOLD WAT!!! //YV/Y TOR W M. DUNCANA r TOR/YE Y5 Dec. 8, 1925- w. M. DUNCAN METHOD OF mmmmmecomsuswx on INFURNACES Filed Jan. 17, 1924 4 sheets sheet 3 A r TOR/7E Y5 De c. 8,1925- w. M. DUNCAN METHOD OF MAINTAINING COMBUSTION IN FURNACES FiledJan. 17, 1924 4 Sheets-Sheet 4 A r TOR/YE vs atented Dee. 1925.

UNlTED STATE VIILLIAIii Ili. DUNCAN, OE ALTON, ILLINGIfi METHOD OFMAINTAINING COMBUSTION IN FURNACES.

Application filed January 17, 1924. Serial No. 686,?63.

To all whom 2'0 may concern.-

Be it known that I, Wnmnmr M. DUNCAN, a citizen of the United States ofAn'1erica, a resident. of Alton, in the county of lrfadison, State ofIllinois, have invented certain new and useful Improvements in Methodsof iiiiaintaining Combustion in Furnaces, of which the following is afull, clear, and exact description, reference being had to theaccompanying drawing, fori'ning a part of this specification.

This invention relates to improvements in methods of maintainingcombustion in furnaces, and the new method is preferably carried out ina furnace wherein the fuel and ashes, or other residual matter, areconfined by the walls of the con'lbustiou chamher.

One of the objects is to provide a method wherein ashes, or the like,may be continually fed away from the confined fuel. Another object is tocontinually add fresh fuel to the bed of fuel confined by the combustionchamber.

A. further object is to produce a draft for efficient combustion in afurnace of this kind.

To illustrate the invention 1 have shown a cylindrical combustionchamber surrounding and confining a bed of ashes with the fuel supportedthereon. Instead of using a grate for the admission of draft to thefuel, the bed of ashes seals the bottom of the combustion chamber, and aforced draft may be admitted between the ashes and the fuel. Additionaldraft is preferably admitted above the bed of fuel. While the ash sealis maintained at the bottom of the coml'mstion chamber, ashes may becontinually fed away from the bottom of the seal, and fresh fuel may becontinually fed onto the top of the confined fuel bed. The coinbustionchamber may have a hollow wall wherein water is confined to be heatedand at the same time prevent overheating of the wall. The draft ispreferably heated by passing through a portion of this hollow wall.

This method has many advantages not present in the ordinary mechanicalstoker consisting of an endless chain grate on which fuel and ashes areconveyed from the front to the rear of a combustion chamber. The newmethod can be carried out in an inexpensive furnace having a relativelyhigh fuel capacity. The fuel can be rapidly consumed by regulating theforced drafts above the ash seal, so as to generate a very intense heatin a small and inexpensive furnace. The desired conditions'can be easilyobtained by regulating the admission of fuel, the discharge of ashes,and the admission of draft. The ash discharge can be controlledindependently of the mechanical stoker whereby the fuel is admitted, andthe body of ashes does not interfere with the admission of draft whichcan be regulated independently of the fuel and ashes.

The new method can be followed in the heating of boilers and variousother apparatus, or in the manufacture of gas or coke.

Fig. I is a side elevation, partly in section illustrating a furnaceadapted for use in carrying out the new method.

Fig. II. is an enlarged vertical section of the furnace.

Fig. III is a horizontal section on the line IIIIII in Fig. II.

Fig. 1V is a section on the line IVTV in Fig. II.

The cylindrical combustion chamber herein shown comprises hollow lowersections 1, 2 and 3, hollow intermediate sections 4.: made of refractorymaterial resting upon the lower sections, and upper sections 5 and 6supported on the sections 4t. The hot gases may pass from the top of thecombustion chamber to a boiler (Fig. I) comprising a shell 7, headers 8and tubes 9 connecting the headers.

In Fig. 11, A designates a bed of fuel confined by the surrounding wallsof the combustion chamber and resting upon a bed of ashes B, or otherresidual matter, which is likewise confined by the combustion chamber.This chamber is open at the bottom and the residual matter rests upon afeeder 9, preferably an endless conveyor located below the combustionchamber and mounted on sprocket wheels 10. One side of the combustionchamber is provided with an outlet at 11 (Fig. II) for the discharge ofashes, and the like, and the conveyor 9 travels across the open bottomof the combustion chamber in the direction indicated by arrows tocontinually feed the ashes through said outlet and thence to a pit 12.

The upper portion of the combustion chamber is provided with aperipheral fuel inlet between the sections 5 and 6, this inlet beingformed around the combustion chamher to receive fuel from hoppers 13.Each hopper has an opening 14 (Fig. II) at the bottom for the dischargeof fuel. Plungers 15 reciprocate in the fuel inlet to force the fuelfrom the openings 14 to the interior of the combustion chamber where itfalls onto the bed of burning fuel A. The incoming fuel is thusdistributed around the combustion chamber to form a substantially uniform fuel bed on the ashes B.

The means for reciprocating the plungers 14 comprises eccentrics 16fixed to shafts 17, and arms 18 surrounding the eccentrics and pivotedat 19 to the respective plunge-rs.

The shafts 17 are geared together at 20, as shown in Fi III, and one ofsaid shafts is provided with a drive pulley 21 which may be operatedcontinuously. The mechanical stoker is thus driven to continuallydeliver coal to the bed of burning fuel, and the ash conveyor 9 isdriven to continually carry away ashes from the confined fuel.

Draft is admitted through an annular passageway 22 (Fig. II) between theash seal B and the bed of burning fuel.

23 designates an annular chamber surrounding the combustion chamber andcommunicating with the passageway 22, as shown most clearly in Fi II,and 24 is a blower whereby air'is forced through said chamber 23. Theupper sections 5 and 6 may be used to preheat this air. 25 designates aninlet pipe (Figs. II and III) through which cold air is admitted to theupper section of the hollow wall, and 26 is an air conductor leadingfrom the upper section to the sect-ion 5. The air heated in thesesections is transmitted through a conductor 27 to the blower 24.Additional air may be admitted through pipes 28 extending through thecombustion chamber at points above the fuel bed A.

The hollow wall of the combustion chamber can be used as a boiler, or asa means for heating the water passing to the boiler above the furnace.29 designates a pipe through which cold water is admitted to the hollowbottom section 1, and 30 designates pipe connections whereby the wateris conducted from the bottom section to the section 2 and thence to thesection 3, the latter being provided with a discharge pipe 31 (Figs. Iand II) leading to the shell 7 of the boiler.

Instead of being made of a single annular member, each of the hollowsections 1, 2, 3, 5 and 6 may consist of several hollow arcuate membershaving their ends connected by means of nipples 32, as shown in Fig. IV,to provide communication between the adjoining arcuate members.

I claim:

1. The method which comprises burning a bed of fuel on a bed of ashes,moving the lower portion of said bed of ashes away from the upperportion thereof, confining the fuel bed and maintaining an open spacefor combustion above the surface of the burning fuel, feeding fresh fuelinto said open combustion space and distributing it over the surface ofthe burning fuel at the bottom of said space, and introducing air intothe burning fuel.

2. The method which comprises burning a bed of fuel on a bed of ashes,moving the lower portion of said bed of ashes away from the upperportion thereof, confining the fuel bed and maintaining an open spacefor combustion above the surface of the burning fuel, feeding fresh fuelinto said open combustion space and distributing it over the surface ofthe burning fuel at the bottom of said space, introducing air into saidbed of fuel, and introducing air into said open combustion space abovethe surface of the bed of fuel.

3. The method which comprises sealing the bottom of a combustion chamberwith a bed of ashes, burning a bed of fuel on the bed of ashes,maintaining an open space for combustion immediately above the fuel bed,continually dropping fresh fuel into said open space so as to distributeit over the surface of the burning fuel at the bottom of said space,introducing air between the burning fuel and the seal formed by the bedof ashes, introducing air into the open combustion-space above the fuelbed, and contin ually feeding the lower portion of the bed of. ashesaway from the upper portion thereof, so as to remove the ashes and atthe same time maintain the ash seal.

4. The method which comprises sealing the bottom of a combustion chamberwith a bed of ashes, burning a bed of fuel on the bed of ashes,maintaining an open space for combustion immediately above the fuel bed,continually dropping fresh fuel into said open space so as to distributeit over the surface of the burning fuel at the bottom of said space,forcing air into the bed of burning fuel, introducing air into the openconibustion space over the surface of said bed, and conveying ashes awayfrom the bottom of said bed of ashes.

In testimony that I claim the foregoing I hereunto affix my signature.

WILLIAM M. DUNCAN.

